Byron b



Unrrnn STATES PATENT Crates.

BYRON l3. S\VITZER, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE CRANE BROS. MANUFACTURING COMPANY, OF SAME PLACE.

COLLAPSING TAP.

SPECIFICATION forming part of Letters Patent No. 378,380, dated February 21, 1888.

Application filed Octcher15,1S87. Serial No. 252,508. (No model.)

To all whom it may concern.-

Be itknown that I, BYRON B. Swrrznn, a citizen of the United States, residing at Chicago, in the county of Cool; and State of Illinois, have invented a certain new and useful Improvement in Collapsing Taps, which is fully set forth in the following specification, reference beinghad to the accompanying drawings, in which- 7 1 Figure 1 is a side elevation of an apparatus embodying my invention; Fig. 2, a longitudinal sectional view ofthe same, taken on the line 1 l of Fig. 1; Fig. 3, a front end view; Fig. 4, a transverse sectional view taken on the line 2 2 of Fig. 1, and Fig. 5 a view of one of the cutters detached.

Like letters refer to like parts in all the figu res of the drawings.

My invention relates to collapsing taps, or, in other words, to that class of tools employed for cutting female screw-threads, and in which the cutters may be withdrawn when the cut ting is finished, in order to provide for the quick and ready separation of the cutting-tool and the article cut thereby.

The object of my present invention is to provide an instrument ofthis description which shall be simple and cheap in construction and ci'fectivein operation; and to these ends my invention consists in certain novel features, which I will now proceed to describe, and will then particularly point out in the claims.

In the drawings, A represents the head or body of the tap, provided at its rear end with a reduced end, a, by means of which it may be secured in a suitable stock or support. \Vitlr in a suitable recess at the front end of the head A is arranged a cam, I3, provided with a number of inclines, 7), corresponding in number to the number of cutters employed, which in the present instance is four, although the number may of course be varied as desired. The cam 13 is provided with a spindle, B", which extends rearward therefrom into a suitable axial recess formed in the head A to receive the same. This spindle may be provided with a circumferential groove, 1), to receivethe end ofa binding-screw, B, mounted in the head A, and havingits inner end extended into the said groove.

C represents a hand-lever, thcinner end of which is screw-threaded and screws into a correspondingly-threaded aperture, If, in the spindle B, or which is connected to the said spin die in any other suitable manner. The head A is provided with a slot, 0, through which the hand-lever C projects, the said slot extending around the periphery of the head at right angles to the axis thereof, as shown in Fig. i of the drawings.

C represents a stop mounted upon the exterior of thehead Aand conforming to the curva ture thereof, the said stop being arranged at the upper end of theslot c,and being provided with a longitudinal slot, 0, through which a binding screw. C", extends into the head, whereby the said stop may be adjusted so as to project over the slot 0 to a greater or less extent, as desired.

D represents an end disk, secured to the cam B by means of screws (1, or in any other suitable nianneiyand provided with eccentric-slots D, corresponding in number and curvature to the inclines b of the said cam. The cutters E extend radially outward through slots in the head A, their inner ends resting upon the inclines b of the cam B, with which they corre' spend in number. Each cutter is provided with a. pin, 0, at its forward end,which extends into the corresponding slot, D, in the end disk, D.

F represents a covering-plate, secured to the face of the end disk, D, by means of screws f, and serving to conceal and protect the slots D therein and the pins 6, which travel in said slots.

The operation of my improved tap is as follows: The head A is preferably secured in a fixedstock or support in such manner as to prevent any rotation thereof, and the cutters E are then projected to the desired extent by bringing the lever C up into the position shown in the several figures of the drawings, when the cam B, by means of its inclines -b, will force the said cutters outwardin an obvious manner. The cutters being thus in operative position, the article to be tapped is mounted in a suitable rotary chuck, and, being placed in proper relative position, is rotated, and at the same time fed forward to cause the cutters to thread the interior thereof.

When the operation of I00 cutting the thread is completed, the lever O is swung down in the direction indicated by the arrow in Fig. 3, when the cam B and disk D will be rotated in the same direction, and the slots D in the disk will draw the cutters inward by reason of the engagement of their pins 0 with the said slots. The cutters are thus instantly disengaged fromthe work, which maybe instantly removed without the necessity of retracting all the steps employed in the operation of cutting. WVhen the binding-screw B is employed, it may be used after the cutters are adjusted into operative position to clamp the spindle of the cam, and thereby prevent rotation ofthe same, in order to hold the cutters firmly in position; but this screw may be dispensed with, if desired. The stop 0 is employed to limitthe upward motion of the lever O, and consequently the extent to which the cutters E project, which function it accomplishes, in an obvious manner, by being extended to a greater or less degree over the slot 0. This stop is employed in case it is desired to thread the interior of an article of extreme thinness, in the cutting of which there would be danger of cutting entirely through the article or materially weakening or breaking the same in case the cutters are allowed to project to their full extent.

It is obvious that various modifications in the details of construction may be made without departing from the principle of myinvention. For instance, the screw 13 may be dispensed with, as may also the stop 0. Moreover, the disk D is not absolutely necessary, although I prefer to employ the same in order to positively retract the cutters.

It will also be obvious that the head A may be rotated and the article to be cut held in a stationary chuck, although I prefer the mode of operation hereinbefore described. For these reasons I do not limit myself strictly to the precise details hereinbefore described, and shown in the drawings.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is-

1. The combination,with the head provided with the radially-movable cutters and with a peripheral slot, of the cam for actuating the cutters, provided with a spindle extending into said head, and ahand-lever secured to the spindle and extending outward through the slot, substantially as and for the purposes specified.

2. The combination, with the head and the radially-movable cutters provided with forward-projecting pins, of the cam provided with an incline for each cutter, the end disk having eccentric-slots, with which the pins on the cutters engage, a spindle to actuate the cam and extending rearward into the head, and a hand-lever secured to said spindle and extending radially outward through a suit-able slot in the head, substantially as and for the purposes specified.

3. The combination, with the head A, pro- Vided with slots 0, of the radially-movable cutters E, the cam B and its spindle B, the hand lever O, and the adjustable stop 0'. substantially as and for the purposes specified.

BYRON 13.. SWITZER. \Vitnesses:

CARRIE FEIGEL, IRVINE MILLER. 

